Troubleshooting Lev, Fcv Problems; General Overview On Lev Operation - Mitsubishi Electric PUHY-M200YNW-A1 Service Handbook

[8-8 Troubleshooting LEV, FCV Problems ]

8-8 Troubleshooting LEV, FCV Problems
8-8-1

General Overview on LEV Operation

LEV2 (Outdoor unit: Linear expansion valve) is stepping-motor-driven valves that operate by receiving the pulse signals from
the outdoor unit control board.
(1) Outdoor LEV (LEV2)
The valve opening changes according to the number of pulses.
1) Outdoor unit control board and the LEV (Outdoor unit: Linear expansion valve)
LEV
Blue
4
Red
6
M
Yellow
2
5
1
White Orange
2) Pulse signal output and valve operation
Output
(phase)
number
1
1 ON
2 ON
3 OFF
4 OFF
3) LEV closing and opening operation
Valve closed
A
E
B
80 - 100 pulses
BS_08_E
ø4
ø3
ø2
ø1
Output state
2 3 4
OFF OFF ON
ON OFF OFF
ON ON OFF
OFF ON ON
D
C
Valve open
Fully open
. 1400 pulses (indoor unit LEV) *1
. 2100 pulses (outdoor unit LEV) *1
Pulses
Control board
6
Red
5
Blue
4
Orange
3
Yellow
2
1
White
Output pulses change in the following orders when the
Valve is closed; 1 2
Valve is open; 4 3
*1. When the LEV opening angle does not change,
all the output phases will be off.
*2. When the output is open phase or remains ON,
the motor cannot run smoothly, and rattles and vibrates.
*Upon power on, the indoor unit circuit board sends a 2200 pulse
signal to the indoor unit LEV and a 3200 pulse signal to the outdoor
unit LEV to determine the valve position and always brings the valve to
the position as indicated by " A " in the diagram.
When the valve operates smoothly, no sound from LEV or no vibration
occurs, however, when the pulses change from E to A in the chart or
the valve is locked, a big sound occurs.
*Whether a sound is generated or not can be determined by
holding a screwdriver against it, then placing your ear against the handle.
*1 The LEV opening may become greater depending on the operation status.
DC12V
Drive circuit
ø4
ø3
ø2
ø1
3 4 1
2 1 4
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